The Infrared Spectrum of Magnesium (1800 < σ < 9000 cm⁻¹) and an Extension of the Term Systems of Mg I and Mg II

The spectrum of neutral and singly ionized magnesium produced by a hollow-cathode discharge has been observed by the Fourier transform spectroscopy technique between 1800 and 9000 cm-1. The observations reported here have allowed an extension of the term systems of Mg I and Mg II; more particularly, first observational evidence is reported for 3s ng1,3G(n ⩽ 8) terms of Mg I and ni2I(n ⩽ 10) terms of Mg II. The results are also used for refining the identification of magnesium lines in the solar photospheric spectrum.